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<a href="struc__fwd_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow-IPC: Structured Transport</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright (c) 2023 Akamai Technologies, Inc.; and other contributors.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> * Each commit is copyright by its respective author or author&#39;s employer.</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> *</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * Licensed under the MIT License:</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> *</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * Permission is hereby granted, free of charge, to any person obtaining a copy</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> * of this software and associated documentation files (the &quot;Software&quot;), to deal</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> * in the Software without restriction, including without limitation the rights</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * copies of the Software, and to permit persons to whom the Software is</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * furnished to do so, subject to the following conditions:</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> *</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * The above copyright notice and this permission notice shall be included in</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * all copies or substantial portions of the Software.</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> *</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"> * THE SOFTWARE IS PROVIDED &quot;AS IS&quot;, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR</span></div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment"> * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"> * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span><span class="comment"> * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER</span></div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="comment"> * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="comment"> * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="comment"> * THE SOFTWARE. */</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="comment"></span> </div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="comment"></span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span> </div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="preprocessor">#include &quot;<a class="code" href="transport__fwd_8hpp.html">ipc/transport/transport_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="preprocessor">#include &lt;flow/util/blob.hpp&gt;</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="preprocessor">#include &lt;capnp/message.h&gt;</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="preprocessor">#include &lt;boost/uuid/uuid.hpp&gt;</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"></span> </div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment">/**</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> * Sub-module of Flow-IPC module ipc::transport providing transmission of structured messages specifically.</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * See ipc::transport doc header.  As that notes, the big daddy here is struc::Channel.</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> *</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * Be aware of sub-namespace ipc::transport::struc::shm which concerns itself with end-to-end-zero-copyable</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> * messages leveraging in-SHM storage.  Normally there&#39;s no need for the user to know or worry about it,</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> * but for advanced applications, particularly extensions and customizations, one might delve into this area of</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> * the code.  Otherwise it&#39;ll be used silently as important glue between various systems.  Your journey would</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> * like start with the struc::Builder concept doc header which would then lead you to</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> * struc::shm::Builder impl.  That might lead you to specific SHM-providers like ipc::shm::classic.</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> */</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceipc_1_1transport_1_1struc.html">ipc::transport::struc</a></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span>{</div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span> </div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span> </div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment">// Find doc headers near the bodies of these compound types.</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span> </div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Message_body, <span class="keyword">typename</span> Struct_builder_config&gt;</div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="keyword">class </span>Msg_out;</div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Message_body, <span class="keyword">typename</span> Struct_reader_config&gt;</div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="keyword">class </span>Msg_in;</div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span> </div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="keyword">class </span>Channel_base;</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Channel_obj, <span class="keyword">typename</span> Message_body,</div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span>         <span class="keyword">typename</span> Struct_builder_config, <span class="keyword">typename</span> Struct_reader_config&gt;</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="keyword">class </span><a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc_1_1shm_1_1classic.html#ac543b500a85f556564e592cbbefb6185">Channel</a>;</div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span> </div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="keyword">class </span>Heap_fixed_builder;</div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="keyword">class </span>Heap_reader;</div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span> </div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="keyword">struct </span>Null_session;</div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"></span> </div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment">/// Alias for capnp&#39;s MessageBuilder interface.  Rationale: as part of our API, we use our identifier style.</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno"><a class="line" href="namespaceipc_1_1transport_1_1struc.html#a52405569bf63eaef55f3c2435c885abc">   67</a></span><span class="comment"></span><span class="keyword">using </span><a class="code hl_class" href="classCapnp__msg__builder__interface.html">Capnp_msg_builder_interface</a> = ::capnp::MessageBuilder;</div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"></span> </div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment">/**</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> * A type used by struc::Channel for internal safety/security/auth needs.  See in particular</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * struc::Channel constructors, both the regular-channel one and the session-master-channel one.</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> * That said: The user of ipc::transport (aided by ipc::session) structured layer shall generally be unconcerned</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> * with this, in practice, as ipc::session machinery will take care of:</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> *   - setting up the session master struc::Channel which will generate this token during initial setup (log-in);</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> *     and</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment"> *   - setting up further `struc::Channel`s as requested by the user (the preceding bullet&#39;s token shall be</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span><span class="comment"> *     passed to each new struc::Channel and expected internally in all messages).</span></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="comment"> *</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span><span class="comment"> * However, if one plans to *create* a struc::Channel directly (as ipc::session does), then one must have some</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment"> * limited understanding of this guy&#39;s existence (if not the internal details).</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment"> *</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="comment"> * As you can see: internally it is a UUID (RFC 4122 Universally Unique IDentifier) which is 128 bits (16 bytes)</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="comment"> * in size.  It&#39;s also a POD (Plain Old Data object), meaning it&#39;s ctor-free (direct-initialized) and can be</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment"> * `memcpy()`d around and such.  See boost.uuid docs (which are simple).</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment"> *</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment"> * ### Use and rationale thereof ###</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment"> * A session master channel struc::Channel, operating in server mode during the log-in phase, will (as of</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment"> * this writing anyway) generate this using the boost.uuid random UUID generator.  From that point on all</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment"> * channels spawned through that guy (by ipc::session) will be cted with that token value; and all messages both</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment"> * in those channels and the original master channel (after the log-in message exchange) will send this value</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment"> * and ensure any in-message has that value (or immediately hose the channel -- auth failure).  This is a</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment"> * safety (not really security, due to the lack of token invalidation at least) measure.  It will reduce chances</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment"> * that &quot;wires get crossed,&quot; and a message goes into the wrong channel somehow.</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment"> *</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"> * That&#39;s how it&#39;s used.  Is the random-generator method of UUID generation acceptable for this use?</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment"> *</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment"> * A bit of research (starting in the RFC perhaps; or Wikipedia) shows that collisions are so cosmically rare as to</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment"> * make it, quite officially, a non-concern.  Even if one does not accept that, however, suppose a collision does</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment"> * occur: two channels happen to generate the same UUID on the same machine around the same time.  This (essentially</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment"> * impossible) scenario would not cause either channel to break; it would only allow (in theory) a token check</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment"> * to succeed where it shouldn&#39;t, if the fabled wires-crossed scenario occurred.  This is an acceptable level of risk.</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment"> *</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment"> * Conversely, perhaps using UUIDs for this is overkill.  128 bits isn&#39;t heavy, but perhaps something smaller --</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment"> * maybe even much smaller, like 32 bits or even 16 -- would improve perf without really reducing effectiveness</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment"> * given the above rationale.  Indeed that&#39;s worth considering but only in the phase where perf optimization is</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment"> * the explicit goal.  Until then (if that even happens) the ability to use the nice boost.uuid library instead</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment"> * of rolling our own jankier/smaller UUID-like thing (or whatever) is well worth the alleged perf cost.</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment"> *</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment"> * @todo Look into whether something smaller that RFC 4122 UUIDs can and should be used for #Session_token.</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment"> * This would be for perf but may well be unnecessary.  See discussion near this to-do.</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment"> */</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno"><a class="line" href="namespaceipc_1_1transport_1_1struc.html#a6751c05fb6582a34c7c47ac470c4a48b">  113</a></span><span class="keyword">using </span><a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc.html#a6751c05fb6582a34c7c47ac470c4a48b">Session_token</a> = boost::uuids::uuid;</div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment"></span> </div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment">/**</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment"> * Sequence of 1+ `Blob` *pointers* to blobs which must stay alive while these pointers may be dereferenced,</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment"> * intended here to refer to a capnp serialization of a capnp-`struct`.  In each `Blob` [`begin()`, `end()`)</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment"> * is the serialization itself; and space before `begin()` and starting with `end()` may</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment"> * be reserved for framing prefix/postfix to preserve zero-copy when transmitting such serializations over</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment"> * an IPC &quot;wire.&quot;</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment"> */</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno"><a class="line" href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">  122</a></span><span class="keyword">using </span><a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">Segment_ptrs</a> = std::vector&lt;flow::util::Blob*&gt;;</div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment"></span> </div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment">/**</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment"> * Message ID uniquely identifying outgoing message (Msg_out, among all other `Msg_out`s), per channel; and</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment"> * similarly incoming message (Msg_in, among `Msg_in`s), per channel.  0 is a sentinel value and not a valid</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment"> * user message ID.  A message ID pertains to a *sent* or *received* *instance* of a user-created Msg_out</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment"> * (and its in-message countrepart Msg_in).  A given Msg_out can be sent 2+ times through a given</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment"> * struc::Channel and even a *different* struc::Channel; a different message ID will pertain to each</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment"> * of those times for a given struc::Channel.  Therefore there is no #msg_id_t *inside* a user Msg_out.</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment"> *</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment"> * This type is in the public API, as the message ID is made available in certain contexts for:</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment"> *   - referring to an earlier-sent message, such as in struc::Channel::undo_expect_responses(); and</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment"> *   - logging/reporting.</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment"> *</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment"> * It can also be used as a sequence number and is therefore assigned from sequence 1, 2, ... (0 is sentinel).</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment"> *</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span><span class="comment"> * ### Rationale for type used ###</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment"> * Needs to be big enough to where there&#39;s no chance it overflows in a given channel for a given direction.</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment"> * Assume 1 billion messages per second, or about 2^30 msg/s.  That would take 2^(64-30), or 2^34, seconds,</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment"> * or over 500 years, to overflow.  So this should be fine.  Moreover overflow is fine in that case, in practice,</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment"> * if this is used only as a unique ID; it would however in theory present problems if used as a sequence number.</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment"> */</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno"><a class="line" href="namespaceipc_1_1transport_1_1struc.html#af7f35fc7588d97a838274fa25700ead9">  145</a></span><span class="keyword">using </span><a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc.html#af7f35fc7588d97a838274fa25700ead9">msg_id_t</a> = uint64_t;</div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span> </div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment">// Constants.</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment"></span> </div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment">/// A value for which `.is_nil()` is true.</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment"></span><span class="keyword">extern</span> <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc.html#a6751c05fb6582a34c7c47ac470c4a48b">Session_token</a> <a class="code hl_variable" href="namespaceipc_1_1transport_1_1struc.html#ad556d20a2aa2d52b83c7afb73951d47d">NULL_SESSION_TOKEN</a>;</div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment"></span> </div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment">/// The only necessary value of empty-type Null_session.</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment"></span><span class="keyword">extern</span> <span class="keyword">const</span> <a class="code hl_struct" href="structipc_1_1transport_1_1struc_1_1Null__session.html">Null_session</a> <a class="code hl_variable" href="namespaceipc_1_1transport_1_1struc.html#ac70446757444f864afa21a5062bc5b0d">NULL_SESSION</a>;</div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span> </div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span><span class="comment">// Free functions.</span></div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment"></span> </div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment">/**</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment"> * Prints string representation of the given struc::Channel to the given `ostream`.</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment"> *</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment"> * @relatesalso struc::Channel</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment"> *</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment"> */</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Channel_obj, <span class="keyword">typename</span> Message_body,</div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span>         <span class="keyword">typename</span> Struct_builder_config, <span class="keyword">typename</span> Struct_reader_config&gt;</div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Channel.html#a0351bb14f40312b30e6cae4927f3373b">  170</a></span>std::ostream&amp; <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Channel.html#a0351bb14f40312b30e6cae4927f3373b">operator&lt;&lt;</a>(std::ostream&amp; os,</div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span>                         <span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Channel.html">Channel</a>&lt;Channel_obj, Message_body,</div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span>                                       Struct_builder_config, Struct_reader_config&gt;&amp; val);</div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment"></span> </div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment">/**</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> * Prints string representation of the given `Msg_out` to the given `ostream`.</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment"> * Namely it prints via Msg_out::to_ostream()`; be sure to read perf notes on that!</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span><span class="comment"> *</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment"> * @relatesalso Msg_out</span></div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment"> *</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment"> */</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Message_body, <span class="keyword">typename</span> Struct_builder_t&gt;</div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span>std::ostream&amp; <a class="code hl_function" href="namespaceipc_1_1transport_1_1struc.html#ae272f248d74db0486c4d9411715db15d">operator&lt;&lt;</a>(std::ostream&amp; os, <span class="keyword">const</span> <a class="code hl_typedef" href="classipc_1_1transport_1_1struc_1_1Channel.html#a860cc99a701576879ebb5a1db58153cc">Msg_out&lt;Message_body, Struct_builder_t&gt;</a>&amp; val);</div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span><span class="comment"></span> </div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span><span class="comment">/**</span></div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment"> * Prints string representation of the given `Msg_in` to the given `ostream`.</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment"> *</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span><span class="comment"> * @relatesalso Msg_in</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment"> *</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment"> */</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Message_body, <span class="keyword">typename</span> Struct_reader_config&gt;</div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span>std::ostream&amp; <a class="code hl_function" href="namespaceipc_1_1transport_1_1struc.html#ae272f248d74db0486c4d9411715db15d">operator&lt;&lt;</a>(std::ostream&amp; os, <span class="keyword">const</span> <a class="code hl_typedef" href="classipc_1_1transport_1_1struc_1_1Channel.html#a05d1cd2fc6a81a39c50a24322fb5c165">Msg_in&lt;Message_body, Struct_reader_config&gt;</a>&amp; val);</div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment"></span> </div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span><span class="comment">/**</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span><span class="comment"> * Prints string representation of the given `Heap_fixed_builder` to the given `ostream`.</span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span><span class="comment"> *</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span><span class="comment"> * @relatesalso Heap_fixed_builder</span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span><span class="comment"> *</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span><span class="comment"> */</span></div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span>std::ostream&amp; <a class="code hl_function" href="namespaceipc_1_1transport_1_1struc.html#ae272f248d74db0486c4d9411715db15d">operator&lt;&lt;</a>(std::ostream&amp; os, <span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder.html">Heap_fixed_builder</a>&amp; val);</div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment"></span> </div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment">/**</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment"> * Prints string representation of the given `Heap_reader` to the given `ostream`.</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment"> *</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment"> * @relatesalso Heap_reader</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment"> *</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment"> */</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span>std::ostream&amp; <a class="code hl_function" href="namespaceipc_1_1transport_1_1struc.html#ae272f248d74db0486c4d9411715db15d">operator&lt;&lt;</a>(std::ostream&amp; os, <span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1Heap__reader.html">Heap_reader</a>&amp; val);</div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span> </div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span>} <span class="comment">// namespace ipc::transport::struc</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span><span class="comment"></span> </div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment">/**</span></div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment"> * `sync_io`-pattern counterparts to async-I/O-pattern object types in parent namespace ipc::transport::struc.</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span><span class="comment"> * Namely transport::struc::sync_io::Channel &lt;=&gt; transport::struc::Channel.</span></div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment"> *</span></div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span><span class="comment"> * @see util::sync_io doc header -- describes the general `sync_io` pattern we are following.</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span><span class="comment"> */</span></div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno"><a class="line" href="namespaceipc_1_1transport_1_1struc_1_1sync__io.html">  237</a></span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceipc_1_1transport_1_1struc_1_1sync__io.html">ipc::transport::struc::sync_io</a></div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span>{</div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span> </div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span> </div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Channel_obj, <span class="keyword">typename</span> Message_body,</div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span>         <span class="keyword">typename</span> Struct_builder_config, <span class="keyword">typename</span> Struct_reader_config&gt;</div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="keyword">class </span><a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1sync__io_1_1Channel.html">Channel</a>;</div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span> </div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">// Free functions.</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span><span class="comment"></span> </div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span><span class="comment">/**</span></div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span><span class="comment"> * Prints string representation of the given struc::sync_io::Channel to the given `ostream`.</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment"> *</span></div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment"> * @relatesalso struc::sync_io::Channel</span></div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span><span class="comment"> *</span></div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment"> */</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Channel_obj, <span class="keyword">typename</span> Message_body,</div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span>         <span class="keyword">typename</span> Struct_builder_config, <span class="keyword">typename</span> Struct_reader_config&gt;</div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno"><a class="line" href="namespaceipc_1_1transport_1_1struc_1_1sync__io.html#a0351bb14f40312b30e6cae4927f3373b">  261</a></span>std::ostream&amp; <a class="code hl_function" href="namespaceipc_1_1transport_1_1struc_1_1sync__io.html#a0351bb14f40312b30e6cae4927f3373b">operator&lt;&lt;</a>(std::ostream&amp; os,</div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span>                         <span class="keyword">const</span> <a class="code hl_class" href="classipc_1_1transport_1_1struc_1_1sync__io_1_1Channel.html">Channel</a>&lt;Channel_obj, Message_body,</div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span>                                       Struct_builder_config, Struct_reader_config&gt;&amp; val);</div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span> </div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span>} <span class="comment">// namespace ipc::transport::struc::sync_io</span></div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment"></span> </div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">/**</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment"> * Small group of miscellaneous utilities to ease work with capnp (Cap&#39;n Proto), joining its `capnp` namespace.</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment"> * As of this writing circumstances have to very particular and rare indeed for something to actually be added</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment"> * by us to this namespace.  As I write this, it contains only `oparator&lt;&lt;(std::ostream&amp;, capnp::Text::Reader&amp;)`.</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment"> */</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespacecapnp.html">capnp</a></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span>{</div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment"></span> </div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">/**</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment"> * Prints string representation of the given `capnp::Text::Reader` to the given `ostream`.</span></div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span><span class="comment"> *</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment"> * ### Rationale for existence ###</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment"> * Well, capnp does not provide it, even though it provides a conversion operator to `string` and such; and</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span><span class="comment"> * it&#39;s nice to be able to print these (particularly when logging with `FLOW_LOG_*()`).</span></div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment"> * For whatever reason the auto-conversion operator does not &quot;kick in&quot; when placed in a</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span><span class="comment"> * an `ostream&lt;&lt;` context; so such printing does not compile (nor does `lexical_cast&lt;string&gt;`).</span></div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment"> *</span></div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment"> * It won&#39;t be forced on anyone that doesn&#39;t include the present detail/ header.</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span><span class="comment"> *</span></div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span><span class="comment"> * @param val</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment"> */</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span>std::ostream&amp; <a class="code hl_function" href="namespacecapnp.html#a8ce2ee1369a8ff7c8bd2ea75ca8af067">operator&lt;&lt;</a>(std::ostream&amp; os, <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc_1_1shm_1_1classic.html#af94f8698ca62a84d6366aaa931375d41">Text::Reader</a>&amp; val);</div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span> </div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span>} <span class="comment">// namespace capnp</span></div>
<div class="ttc" id="aclassCapnp__msg__builder__interface_html"><div class="ttname"><a href="classCapnp__msg__builder__interface.html">Capnp_msg_builder_interface</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Channel_html"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Channel.html">ipc::transport::struc::Channel</a></div><div class="ttdoc">Owning and wrapping a pre-connected transport::Channel peer (an endpoint of an established channel ov...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8hpp_source.html#l00586">channel.hpp:589</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Channel_html_a0351bb14f40312b30e6cae4927f3373b"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Channel.html#a0351bb14f40312b30e6cae4927f3373b">ipc::transport::struc::Channel::operator&lt;&lt;</a></div><div class="ttdeci">std::ostream &amp; operator&lt;&lt;(std::ostream &amp;os, const Channel&lt; Channel_obj, Message_body, Struct_builder_config, Struct_reader_config &gt; &amp;val)</div><div class="ttdoc">Prints string representation of the given struc::Channel to the given ostream.</div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Channel_html_a05d1cd2fc6a81a39c50a24322fb5c165"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Channel.html#a05d1cd2fc6a81a39c50a24322fb5c165">ipc::transport::struc::Channel::Msg_in</a></div><div class="ttdeci">typename Sync_io_obj::Msg_in Msg_in</div><div class="ttdoc">Encapsulation of any in-message instance received by a *this of this type.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8hpp_source.html#l00639">channel.hpp:639</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Channel_html_a860cc99a701576879ebb5a1db58153cc"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Channel.html#a860cc99a701576879ebb5a1db58153cc">ipc::transport::struc::Channel::Msg_out</a></div><div class="ttdeci">typename Sync_io_obj::Msg_out Msg_out</div><div class="ttdoc">Encapsulation of any out-message payload sent or meant to be sent via send() (et al) by a *this of th...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8hpp_source.html#l00630">channel.hpp:630</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder_html"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder.html">ipc::transport::struc::Heap_fixed_builder</a></div><div class="ttdoc">Implements Struct_builder concept by straightforwardly allocating fixed-size segments on-demand in th...</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8hpp_source.html#l00130">heap_serializer.hpp:132</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__reader_html"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__reader.html">ipc::transport::struc::Heap_reader</a></div><div class="ttdoc">Implements Struct_reader concept by straightforwardly interpreting a serialization by Heap_fixed_buil...</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8hpp_source.html#l00324">heap_serializer.hpp:327</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1sync__io_1_1Channel_html"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1sync__io_1_1Channel.html">ipc::transport::struc::sync_io::Channel</a></div><div class="ttdoc">sync_io-pattern counterpart to async-I/O-pattern transport::struc::Channel.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2sync__io_2channel_8hpp_source.html#l00322">channel.hpp:326</a></div></div>
<div class="ttc" id="anamespacecapnp_html"><div class="ttname"><a href="namespacecapnp.html">capnp</a></div><div class="ttdoc">Small group of miscellaneous utilities to ease work with capnp (Cap'n Proto), joining its capnp names...</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8cpp_source.html#l00187">heap_serializer.cpp:188</a></div></div>
<div class="ttc" id="anamespacecapnp_html_a8ce2ee1369a8ff7c8bd2ea75ca8af067"><div class="ttname"><a href="namespacecapnp.html#a8ce2ee1369a8ff7c8bd2ea75ca8af067">capnp::operator&lt;&lt;</a></div><div class="ttdeci">std::ostream &amp; operator&lt;&lt;(std::ostream &amp;os, const Text::Reader &amp;val)</div><div class="ttdoc">Prints string representation of the given capnp::Text::Reader to the given ostream.</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8cpp_source.html#l00190">heap_serializer.cpp:190</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_1_1shm_1_1classic_html_ac543b500a85f556564e592cbbefb6185"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc_1_1shm_1_1classic.html#ac543b500a85f556564e592cbbefb6185">ipc::transport::struc::shm::classic::Channel</a></div><div class="ttdeci">struc::Channel&lt; Channel_obj, Message_body, Builder::Config, Reader::Config &gt; Channel</div><div class="ttdoc">Convenience alias: Use this when constructing a struc::Channel with tag Channel_base::S_SERIALIZE_VIA...</div><div class="ttdef"><b>Definition:</b> <a href="transport_2struc_2shm_2classic_2classic_8hpp_source.html#l00041">classic.hpp:42</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_1_1shm_1_1classic_html_af94f8698ca62a84d6366aaa931375d41"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc_1_1shm_1_1classic.html#af94f8698ca62a84d6366aaa931375d41">ipc::transport::struc::shm::classic::Reader</a></div><div class="ttdeci">Reader&lt; ipc::shm::classic::Pool_arena &gt; Reader</div><div class="ttdoc">Convenience alias: transport::struc::shm::Reader that works with boost.ipc.shm pools from ipc::shm::c...</div><div class="ttdef"><b>Definition:</b> <a href="transport_2struc_2shm_2classic_2classic__fwd_8hpp_source.html#l00039">classic_fwd.hpp:39</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_1_1sync__io_html"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc_1_1sync__io.html">ipc::transport::struc::sync_io</a></div><div class="ttdoc">sync_io-pattern counterparts to async-I/O-pattern object types in parent namespace ipc::transport::st...</div><div class="ttdef"><b>Definition:</b> <a href="struc__fwd_8hpp_source.html#l00237">struc_fwd.hpp:238</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_1_1sync__io_html_a0351bb14f40312b30e6cae4927f3373b"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc_1_1sync__io.html#a0351bb14f40312b30e6cae4927f3373b">ipc::transport::struc::sync_io::operator&lt;&lt;</a></div><div class="ttdeci">std::ostream &amp; operator&lt;&lt;(std::ostream &amp;os, const Channel&lt; Channel_obj, Message_body, Struct_builder_config, Struct_reader_config &gt; &amp;val)</div><div class="ttdoc">Prints string representation of the given struc::sync_io::Channel to the given ostream.</div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html">ipc::transport::struc</a></div><div class="ttdoc">Sub-module of Flow-IPC module ipc::transport providing transmission of structured messages specifical...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8cpp_source.html#l00030">channel.cpp:31</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_a6751c05fb6582a34c7c47ac470c4a48b"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#a6751c05fb6582a34c7c47ac470c4a48b">ipc::transport::struc::Session_token</a></div><div class="ttdeci">boost::uuids::uuid Session_token</div><div class="ttdoc">A type used by struc::Channel for internal safety/security/auth needs.</div><div class="ttdef"><b>Definition:</b> <a href="struc__fwd_8hpp_source.html#l00113">struc_fwd.hpp:113</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_a82a69eaa39cbe8a002de1266f1cbb5cb"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">ipc::transport::struc::Segment_ptrs</a></div><div class="ttdeci">std::vector&lt; flow::util::Blob * &gt; Segment_ptrs</div><div class="ttdoc">Sequence of 1+ Blob pointers to blobs which must stay alive while these pointers may be dereferenced,...</div><div class="ttdef"><b>Definition:</b> <a href="struc__fwd_8hpp_source.html#l00122">struc_fwd.hpp:122</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_ac70446757444f864afa21a5062bc5b0d"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#ac70446757444f864afa21a5062bc5b0d">ipc::transport::struc::NULL_SESSION</a></div><div class="ttdeci">const Null_session NULL_SESSION</div><div class="ttdoc">The only necessary value of empty-type Null_session.</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8cpp_source.html#l00035">heap_serializer.cpp:35</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_ad556d20a2aa2d52b83c7afb73951d47d"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#ad556d20a2aa2d52b83c7afb73951d47d">ipc::transport::struc::NULL_SESSION_TOKEN</a></div><div class="ttdeci">const Session_token NULL_SESSION_TOKEN</div><div class="ttdoc">A value for which .is_nil() is true.</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8cpp_source.html#l00035">channel.cpp:35</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_ae272f248d74db0486c4d9411715db15d"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#ae272f248d74db0486c4d9411715db15d">ipc::transport::struc::operator&lt;&lt;</a></div><div class="ttdeci">std::ostream &amp; operator&lt;&lt;(std::ostream &amp;os, const Heap_fixed_builder &amp;val)</div><div class="ttdoc">Prints string representation of the given Heap_fixed_builder to the given ostream.</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8cpp_source.html#l00132">heap_serializer.cpp:132</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_af7f35fc7588d97a838274fa25700ead9"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#af7f35fc7588d97a838274fa25700ead9">ipc::transport::struc::msg_id_t</a></div><div class="ttdeci">uint64_t msg_id_t</div><div class="ttdoc">Message ID uniquely identifying outgoing message (Msg_out, among all other Msg_outs),...</div><div class="ttdef"><b>Definition:</b> <a href="struc__fwd_8hpp_source.html#l00145">struc_fwd.hpp:145</a></div></div>
<div class="ttc" id="astructipc_1_1transport_1_1struc_1_1Null__session_html"><div class="ttname"><a href="structipc_1_1transport_1_1struc_1_1Null__session.html">ipc::transport::struc::Null_session</a></div><div class="ttdoc">Value for Struct_builder::Session when no extra information is needed when serializing Struct_builder...</div><div class="ttdef"><b>Definition:</b> <a href="heap__serializer_8hpp_source.html#l00045">heap_serializer.hpp:45</a></div></div>
<div class="ttc" id="atransport__fwd_8hpp_html"><div class="ttname"><a href="transport__fwd_8hpp.html">transport_fwd.hpp</a></div></div>
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